A digital certificate problem that led Microsoft to temporarily suspend publishing new and upgraded Windows Phone applications on Tuesday has been fixed, the software giant said Thursday.

"It will take a day or two for the repair to fully deploy and newly-published apps to begin appearing in Marketplace again," noted Windows Marketplace Senior Director Todd Brix.

The issue only affected handsets upgraded to Windows Phone 7.5 from an earlier version, but Microsoft nevertheless decided to stop accepting new apps to devote its full attention to fixing the glitch. And fortunately for app developers, the temporary snafu only affected a small percentage of the 100,000-plus apps in Windows Phone Marketplace.

"I think this was a hiccup that likely will not have enduring effects in the long run," said Al Hilwa, director of applications software development at IDC. "The platform is in transition right now and the ecosystem is both excited and apprehensive, Hilwa told us Friday.

Growing Pains

Brix attributed this week's digital certificate problem to Microsoft's ongoing deployment of a new Windows Phone Dev Center, which includes a completely rebuilt back-end infrastructure. "In an earlier blog post I mentioned the possibility that we might encounter some hiccups during this complex rollout and changeover [and] we did," Brix wrote.

At the end of last month, Brix had cautioned developers that they might still encounter an occasional hiccup as Microsoft completes the back-end work on Windows Phone Dev Center over the next several weeks. "The good news is that this brief inconvenience will result in a more robust submission and for your Windows Phone 7.5 apps," Brix said.

The need for a back-end infrastructure upgrade became apparent at the end of this year's first quarter, when Microsoft noticed that the number of apps in the Windows Phone Marketplace had grown by 60 percent. As a result of growing pains, Brix noted, new app certification turnaround times had increased by one business day, on average, between the end of last year and the beginning of April.

Developer Interest Remains High

Fortunately for Microsoft, the company's infrastructure refresh is slated to be finished before the end of this summer -- well in advance of the software giant's highly anticipated roll out of next-generation WP8, Windows 8 and Windows RT platforms. Still, Hilwa noted that Microsoft has a lot of work to do to help developers make a smooth transition to the new mobile platform.

"The development model has not been officially explained and so it is hard for developers to get a headstart on the new platform," Hilwa said Friday. "On the other hand, investment in the 7.x Silverlight-based model is winding down -- resulting in less than ideal application availability for the next few months in general, and especially for 7.x device owners."

Unofficial info from the leaked SDK (software developer kit) suggests that the development model, while similar to Windows 8, is not identical, Hilwa noted. "Similarity is good as it drives more convergence across form-factors which can leverage the same or similar code-bases, but differences can highlight that yet another potentially disruptive change may come down the road," Hilwa said.

Having seen the platform go through many changes, Hilwa believes that developers would be wise to have doubts. "Overall however, Microsoft is on track to converge platforms, but they have to work harder not to leave devices and technologies behind in the future, as it can impact the long-term credibility of the effort," Hilwa said.